well-nigh vs virtually

well-nigh and virtually both are adverbs.

Word	Noun	Adjective	Verb	Adverb
well-nigh	No	No	No	Yes
virtually	No	No	No	Yes

As adverbs, well-nigh and virtually are synonyms defined as:

well-nigh and virtually: (of actions or states) slightly short of or not quite accomplished; all but

Other synonyms of well-nigh include about, almost, most, near, nearly, nigh.

well-nigh (adverb)	virtually (adverb)
(of actions or states) slightly short of or not quite accomplished; all but	in essence or effect but not in fact
	(of actions or states) slightly short of or not quite accomplished; all but